Properties of Semiconductor

PROPERTIES OF SEMICONDUCTOR

1. The resistivity of semiconductors lies between conducting and insulating materials. (i.e.,) 10^-4 to 0.5 ohm - metre..

2. At 0 K they behave as insulators.

3. When the temperature is raised or when impurities are added, their conductivity increases. i.e., ρ ∞ 1/T

(This is converse compared to usual conductors for which ρ∞ T.)

4. They have negative temperature co-efficient of resistance.

Explanation

The reason for the above property is, when the temperature is increased, large number of charge carriers are produced due to breaking of covalent bonds and hence these electrons move freely and gives rise to conductivity.

5. In conductors the electrons are charge carriers and will take part in conduction but in semiconductor both electrons and holes are charge carriers and will take part in conduction. (Hole is produced by the vacancy of electrons at bond sites).

Total conductivity, σ = σ_e + σ _h

Where, σ_e - conductivity due to electrons.

σ _h - conductivity due to holes.